This invention relates to a truck having a driver's cab which is tiltably coupled in an articulated fashion by means of a driver's cab bearing to a chassis located underneath it. The driver's cab can as a result be pivoted away in the upward direction for maintenance and repair work in the engine compartment, and in the normal operating state, the cab is connected to the chassis by means of the bearing and anchoring devices as well as spring devices.
Such trucks have a driver's cab which is located at a relatively high position above the drive train and with which there is the risk that, when there is a head-on collision with an obstacle at the level of the driver's cab, the attachments of the driver's cab rupture and severe damage occurs to the driver's cab. This is due to the fact that the connecting points of the driver's cab do not have sufficient strength to withstand large collision forces. The driver's cab can therefore suffer considerable deformation in the event of a crash and, as a result, considerable injury to the vehicle occupants can also occur. The damage to the truck is considerable when there is such a head-on impact with, for example, a bridge abutment or a trailer of a truck traveling ahead, referred to as a platform collision, and frequently result in total write-offs. The driver's cab often has to absorb a very large amount of energy, which can be deflected only partially into the chassis before the driver's cab bearing ruptures. The driver's cab is often completely destroyed in such a case.
The invention relates to such a truck having a driver's cab which is located at a high position and is provided with a collision restraint system for the driver's cab. In order to avoid the problems described, it is, in fact, known to provide, in addition to the customary connecting points of the driver's cab in the closed state, a mechanical rigid anchoring between the driver's cab and the chassis as an additional restraint system. Such additional structures are costly owing to the difference in the level between the driver's cab and the fixed components of the chassis located beneath it, and are generally heavy. Also, owing to the need for tilting mobility of the driver's cab and relative mobility in order to provide suspension for the driver's cab they also require costly structures, for example using lever mechanisms, with a large number of individual components.
German document DE 195 80 267 T1 discloses a truck having a driver's cab which is tiltably mounted above a drive train and which is coupled in an articulated fashion with respect to a bottom chassis by means of a bearing, wherein the drive train is attached to the chassis. Furthermore, a restraint system is provided for the driver's cab, which restraint system is suitable, in the case of head-on collisions of the truck with an obstacle at the level of the driver's cab, for absorbing and deflecting collision forces at the driver's cab. The restraint system establishes a fixed connection between the driver's cab and a fixed part of the drive train located underneath it. In order to achieve the highest possible level of comfort for the driver in terms of suspension without sound vibrations being transmitted into the driver's cab from the frame, one of the stabilizer bearings on the vehicle is embodied as a bushing which behaves in a soft fashion in the longitudinal and transverse directions but in a rigid fashion in the vertical direction.
German document DE 198 02 632 B4 describes a utility vehicle having a vehicle frame and a driver's cab which is coupled in an articulated fashion to the vehicle frame so as to be tiltable at the front about a transverse axis. At the rear, the driver's cab is supported on a bridge crossbeam and locked. The bridge crossbeam is arranged centrally and symmetrically in its position relative to the driver's cab and serves to implement an elastic support and to lock the driver's cab to the vehicle frame. The bridge crossbeam is composed of a horizontally arranged cross chord with limbs which extend in a vertically oblique fashion downward to the vehicle frame. By way of the limbs, the crossbeam is mounted, by corresponding attachment elements, to the frame longitudinal beams. In the event of a head-on impact, the driver's cab is pushed rearward, in which case the bridge crossbeam is deformed as far as the vehicle frame without individual elements rupturing, and in the process it can effectively dissipate energy.
In contrast with the above, the present invention has the object of proposing a truck which is more resistant to head-on collisions at the level of the driver's cab and can be implemented with low additional complexity and cost.
This object is achieved with a truck having the features claimed.
Advantageous refinements and developments are also claimed.
The truck according to the invention has a driver's cab which is tiltably mounted above a drive train, and a restraint system for the driver's cab in the case of head-on collisions of the driver's cab with obstacles at the level of the driver's cab in order to absorb and deflect collision forces. The restraint system comprises a flexible coupling element which establishes a connection, which is resistant to tensile stress counter to the direction of travel, between the driver's cab and a front fixed part of the drive train located beneath it. The flexible coupling element which is resistant to tensile stress permits an effective mechanical coupling between a fixed part in the front, low-lying region of the engine compartment to the driver's cab located above it, for the purpose of deflecting collision forces without the possibility of the driver's cab tilting or the necessary intrinsic mobility of the drive train and of the driver's cab being adversely affected. The forces which act on the driver's cab are in this way passed on to the drive train, i.e. the drive engine, the gearbox, the cardan shaft and the rear wheel axle, and are absorbed by the latter. Flexibility of the coupling element is understood here to be freedom from bending which permits free tilting about the bearing of the driver's cab. Nevertheless, the coupling element is essentially resistant to tensile stress, i.e. it permits tensile forces to be transmitted from the driver's cab to the drive train. The loading on the driver's cab can therefore be taken up by the driver's cab structure without a large degree of expenditure and transmitted to the drive train with a greater degree of strength. In this way, even at relatively high impact speeds, excessive damage to the driver's cab is prevented. Crash situations at relatively high speeds can therefore be coped with better. The mounting and manufacture of the restraint system according to the invention are conceivably simple and require comparatively little space. The flexible coupling element which is resistant to tensile stress can in this context have different shapes and structures; for example the coupling element can be in the shape of a strap, cable, belt, chain or the like made of metallic or nonmetallic materials.
According to one advantageous refinement of the invention, the coupling element is attached to lateral longitudinal beams of the driver's cab or of a chassis of the driver's cab. In this way the collision forces from the front region of the driver's cab are applied directly to the coupling element even if the latter is attached to a rear section of the driver's cab. The coupling element therefore extends from a rear attachment point on the longitudinal beams obliquely toward the front and downward for connection to a fixed part of the drive train. The lateral longitudinal beams of the driver's cab structure which are rigid in the longitudinal direction prevent deformation of the driver's cab in the bottom region and the flexible coupling element can easily be attached to the longitudinal beams. As a result of the attachment to the longitudinal beams of the driver's cab, there is no need for additional attachment components on the bodywork of the driver's cab.
According to a further refinement of the invention, the coupling element is attached to an end region of a drive engine. Since the drive engine generally forms the frontmost component of a drive train of a truck, it is therefore possible for the coupling element to be attached as far as possible in the front region and the upward orientation toward the driver's cab is therefore less oblique. The coupling element is attached between an upper, rear section of the driver's cab and a front, preferably end region of the drive train. As a result, a profile which rises obliquely from the front to the rear is obtained. The flatter this profile, the more effective the absorption of tensile forces in the event of collisions. The attachment at the end can be implemented, for example, by means of a corresponding securing part which runs past the front part of the drive engine. The coupling element therefore forms a transverse connection to the front side of the engine, preferably at the level of its greatest strength, which ensures very secure anchoring of the driver's cab. The coupling element can be attached to the engine at, for example, the level of the cylinder head since the latter has a high degree of intrinsic strength and therefore permits large forces to be absorbed in the event of a crash.
According to a further refinement of the invention, the flexible coupling element is a securing cable which is wrapped around the drive engine in a U shape and which is attached by its ends to the lateral longitudinal beams of the chassis of the driver's cab. The flexible coupling element is in this way a single-piece, continuous element which, by virtue of the U-shaped wrapping around the drive engine, ensures reliable anchoring of the driver's cab against forces acting at the front. The manufacture and mounting of the securing cable are conceivably simple. Only the ends of the securing cable have to be attached to the driver's cab and an attachment means for the continuous cable has to be provided on the front side of the engine. This provides, to an equal degree, a cross connection in front of the engine and a bridging of the difference in level between the plane of the driver's cab and the plane of the drive train by means of a single component, specifically the securing cable. It is also not necessary to make any relatively large changes to existing structures since the flexible securing cable is adapted in terms of its profile to the respective spatial conditions.
According to a further refinement of the invention, the coupling element is attached in a rotationally moveably and captive fashion to the sides of the drive train by means of a guide. As a result, the tilting movement of the driver's cab is not impeded and the coupling element remains attached to a predefined position in the front region of the drive train even in the loose, unstressed state. The coupling element is prevented from slipping so that it is always in the position which is optimum in terms of a crash, in particular in the region of high strength of the drive train, such as for example at the level of the cylinder head of the engine.
According to a further advantageous refinement of the invention, the flexible coupling element of the restraint system is attached in a rotationally movable fashion to the driver's cab. A rotationally moveable attachment can be effected, for example, by means of pivot pins which are mounted on the driver's cab. The rotationally movable attachment permits, on the one hand, an unimpeded tilting movement of the driver's cab, and on the other hand, the attachment is only subjected to tensile stress in the direction of the obliquely downward extending coupling element in the case of a collision so that excessive loading of the attachment elements and the risk of rupturing are avoided.
According to a further advantageous refinement of the invention, energy-absorbing crash elements are provided between the driver's cab and the coupling element. If the coupling element is subjected to tensile stress in the case of a collision, at first a mechanical coupling which is resistant to tensile stress is established between the drive train and the driver's cab. When there are very large forces which can no longer be absorbed by the coupling element, the crash elements become deformed starting from a certain value and destroy the applied excess energy. As a result, the flexible coupling element is prevented from rupturing even when there are very large forces, and the connection between the driver's cab/drive train is maintained. In this way it is possible to cope with even relatively high impact speeds by means of the restraint system. The crash elements can be here in any form which is known for this purpose to a person skilled in the art and can be implemented, for example, as deformation elements, active energy-absorbing elements or the like. Alternatively, the coupling element itself can have an extension capability in order to destroy energy through its deformation.
Advantages and features of the invention are explained in the detailed description below in which the invention is described in more detail with respect to the exemplary embodiments illustrated in the appended drawings.